The Gigalight GQS-MPO101-LP is a QSFP28 active electrical loopback module used for testing QSFP28 transceiver ports in board level test. By substituting for a full-featured QSFP28 transceiver, the electrical loopback provides a cost effective low loss method for QSFP28 port testing. The GQS-MPO101-LP is packaged in a standard MSA housing compatible with all QSFP28 ports. Transmit data from the host is electrically routed (internal to the loopback module) to the receive data outputs and back to the host. Since the loopback module does not contain laser diodes, photodiodes, laser driver or transimpedance amplifier chips, etc., it provides an economical way to exercise QSFP28 ports during R&D validation, production testing and field testing. The GQS-MPO101-LP module provides QSFP28 power Class 1, 2, 3, or 4 loading using a customer supplied +3.3V voltage supply. Power Classes 5, 6 and 7 are available upon request.